Let's say you bought that storage system: https://www.dell.com/en-us/dt/storage/powerstore-storage-app... AFAIK, it doesn't come with complete source code, and you could not request all of it.

Let's say you decided to run MongoDB as a service, and you are fine with releasing Service Source Code under SSPL. The problem is – you can't. You don't own the source code for your NAS and can't relicense it. Nothing in the text says, "relicense all you can, and then you are fine". Clause 13 puts requirements on software that are completely unrelated in terms of copyright.

> I am confused. If you use a custom storage system then you would have the code for it. No?

Nothing in the license text says that the storage system has to be custom.

> The idea you need to release code for the os, file system, network routers, etc is absurd.

I agree with you that this is absurd. But that's what the license text says.

I suggest you read section 13, not MongoDB's FAQs or other explanations of how it works. The actual legal tech is very different from what you seem to think it is.